Lubricant blends to reduce refrigerant solubility

ABSTRACT

Compositions, methods, systems, and applications herein are directed to lubricant blends that balance solubility and viscosity of a refrigerant, where in some cases the lubricant blends herein help reduce solubility of a refrigerant. A lubricant blend includes a mixture of two or more different types of lubricants to reduce refrigerant solubility.

FIELD

Embodiments disclosed herein generally relate to lubricant blends. Inparticular, compositions, methods, systems, and applications herein aredirected to lubricant blends that balance solubility and viscosity of arefrigerant, where in some cases the lubricant blends herein help reducesolubility of a refrigerant, which may be implemented in equipment ofvapor compression systems, such as for example, heating, ventilation,air conditioning, and/or refrigeration (HVACR) systems.

BACKGROUND

Vapor compression devices have load bearing surfaces utilizing a widerange of materials. Lubricants are used on these load bearing surfacesto reduce friction and wear. For example, in HVACR systems, utilizingsaturated and unsaturated hydrofluorocarbon (HFC) refrigerants-alsoreferred to as hydrofluoroolefins (HFOs) when unsaturated, may employ apolyol ester (POE) or a polyvinyl ether (PVE) lubricant. A specificlubricant is selected by considering the lubrication requirements of theintended system of use and ensuring that the refrigerant and oil mixtureproperties meet these requirements. In most cases, one specific class oflubricant, such as for example POE, PVE or polyalkylene glycol (PAG) isselected for a vapor compression system.

SUMMARY

When a new refrigerant and lubricant combination is applied to anexisting system design, bearing lubrication requirements (e.g. minimumfilm thickness) for example of a compressor of a vapor compressionsystem, are considerations to be met for an anticipated operationalrange of the vapor compression system. In the case of new system buildssuch considerations are taken into account in the design of the system.While in existing systems, interactions between the new refrigerant andlubricant that are different from the interactions of the refrigerantand lubricant originally present with the designed system can also drivethese considerations.

Different modes of operation for a system may have different lubricationrequirements. For instance a compressor operating at a slower speed orat variable speeds may require a higher viscosity lubricant than thesame type of compressor operating at a single fixed speed with the samerefrigerant. In addition, if the refrigerant is replaced in a specificsystem by an alternative, a different lubricant may be required tocompensate for differences in the solubility between the previousrefrigerant and the new refrigerant. For example, if a refrigerant hashigher solubility in the lubricant, the lubricant is susceptible tolubricant viscosity reduction as compared to a relatively less solublerefrigerant. In such cases, a higher viscosity lubricant can be selectedto compensate for lubricant viscosity reduction when present in amixture of the lubricant and refrigerant. However, using higherviscosity lubricants can require additional power consumption by thesystem to move the relatively higher viscosity fluid, which can impactsystem efficiency, for example during a cold start condition. Inaddition, extra hardware added to the system, for example a lubricantseparator and/or lubricant heater, and/or the use of different systemcontrols, can lead to additional concerns including the increase in thecost of manufacture and on component reliability for such additionalcomponents. Further, if the system operating map is restricted orreduced due to the refrigerant lubricant interaction(s), product salesmay be limited due to the inability to operate under conditionsspecified by certain customers.

Embodiments disclosed herein generally relate to lubricant blends. Inparticular, compositions, methods, systems, and applications herein aredirected to lubricant blends that balance solubility and viscosity of arefrigerant, where in some cases the lubricant blends herein help reducesolubility of a refrigerant, which may be implemented in equipment ofvapor compression systems, such as for example, heating, ventilation,air conditioning, and/or refrigeration (HVACR) systems.

In an embodiment, a lubricant blend includes a mixture of two or moredifferent types of lubricants to reduce refrigerant solubility, forexample in comparison to a single lubricant of the same or similarviscosity grade, or to other lubricant blends.

In an embodiment, a lubricant blend composition includes two or morelubricants. The two or more lubricants include a first lubricant; and asecond lubricant. The first lubricant is present at a higher weightpercentage than the second lubricant, the first lubricant includes ahigher viscosity than the second lubricant, such that when blended withthe second lubricant, the lubricant blend has a resulting viscosity whenmixed with a refrigerant, and the lubricant blend exhibits a suitablemiscibility and solubility within a desired operating range of a vaporcompression system.

In an embodiment, the lubricant blend includes one or more of POE, PVE,and PAG as the first lubricant and one or more of alkylbenzene (AB),polyalphaolefin (PAO), mineral oil, and estolide as the secondlubricant.

In an embodiment, the first lubricant is POE or PVE and the secondlubricant is AB or mineral oil.

In an embodiment, the first lubricant is POE and the second lubricant isAB.

In an embodiment, the lubricant blend is mixed with a refrigerant orrefrigerant blend.

In an embodiment, the refrigerant or refrigerant blend is a relativelysoluble refrigerant type when mixed with a single lubricant. In anembodiment, the refrigerant or refrigerant blend is a low pressurerefrigerant type, which includes for example an olefin refrigerant type.In an embodiment, the refrigerant or refrigerant blend is a refrigeranttype suitable for use in a chiller, for example a fluid chillerimplemented with a centrifugal compressor. In an embodiment, therefrigerant or refrigerant blend is a relatively soluble refrigeranttype and is a low pressure refrigerant type.

In an embodiment, the refrigerant or refrigerant blend is a blend of tworefrigerants.

In an embodiment, the refrigerant or refrigerant blend includes forexample, a blend of R1336mzz(Z) (i.e.cis-1,1,1,4,4,4-hexafluorobut-2-ene) as the first refrigerant andR1130(E) (i.e. trans-1,2-dichloroethylene) as the second refrigerant.

In an embodiment, a fluid for a vapor compression system includes thelubricant blend of any one or more of paragraphs [0005] to [0010] aboveand the refrigerant blend of any one or more of paragraphs [0011] to[0014] above.

In an embodiment, the vapor compression system is a fluid chiller for anHVACR application.

In an embodiment, the fluid chiller includes a centrifugal compressor.

In an embodiment, a method of retrofitting a vapor compression systemincludes removing an existing fluid in the vapor compression system, theexisting fluid includes a refrigerant and lubricant mixture; replacingthe existing fluid in the vapor compression system with a replacementfluid, the replacement fluid includes a replacement refrigerant of anyone or more of paragraphs [0011] to [0014] above and the lubricant blendof any one or more of paragraphs [0005] to [0010] above; and confirmingan operating range of the vapor compression system with the replacementfluid.

A method of reducing the solubility of a refrigerant in a lubricantblend includes selecting a refrigerant of any one or more of paragraphs[0011] to [0014] above for application in a vapor compression system;selecting the lubricant blend of any one or more of paragraphs [0005] to[0010] above to be included as a mixture with the selected refrigerant;confirming the miscibility of the lubricant blend and refrigerant whenmixed together over a desired operating range of the vapor compressionsystem; and confirming a viscosity of the lubricant blend andrefrigerant when mixed together over the desired operating range of thevapor compression system.

DRAWINGS

These and other features, aspects, and advantages of the will becomebetter understood when the following detailed description is read withreference to the accompanying drawing, wherein:

FIG. 1 is a schematic diagram of a vapor compression system, accordingto an embodiment.

FIG. 2 is a a glass tube at ambient conditions (˜20° C.) containing 95%of an example refrigerant blend and 5% mineral oil, where two separatephases formed.

FIG. 3 is a pressure viscosity temperature chart showing a mixtureviscosity of an example refrigerant blend with a lubricant (POE #1) isreduced relative to R-123/mineral oil due to higher refrigerantsolubility of the example refrigerant blend in POE #1.

FIG. 4 is a pressure viscosity temperature chart showing a mixtureviscosity of an example refrigerant blend with a lubricant blend hereinwhere solubility is improved while desired miscibility is maintained.

FIG. 5 is a chart showing the change of critical solution temperature(CST) as refrigerant and lubricant concentrations vary.

FIG. 6 is a chart showing refrigerant solubility of the examplerefrigerant blend with a lubricant blend herein in comparison to theexample refrigerant blend with the POE #1 and relative to R123/mineraloil.

FIG. 7 is a chart showing refrigerant solubility of the examplerefrigerant blend with a lubricant blend herein in comparison to theexample refrigerant blend with the POE #1 and relative to R123/mineraloil.

FIG. 8 shows side sectional view of an embodiment of a bearing, whichmay be employed in a compressor, for example in the system shown in FIG.1.

DETAILED DESCRIPTION

Embodiments disclosed herein generally relate to lubricant blends. Inparticular, compositions, methods, systems, and applications herein aredirected to lubricant blends that balance solubility and viscosity of arefrigerant, where in some cases the lubricant blends herein help reducesolubility of a refrigerant in the lubricant blend, which may beimplemented in equipment of vapor compression systems, such as forexample, heating, ventilation, air conditioning, and/or refrigeration(HVACR) systems.

FIG. 1 is a schematic diagram of a heat transfer circuit 10 according toan embodiment. The heat transfer circuit 10 is an example of a vaporcompression system, which may be implemented as a HVACR system, such asfor example a fluid chiller. In an embodiment, the fluid chiller is acentrifugal chiller, including a centrifugal compressor. The heattransfer circuit 10 generally includes a compressor 12, a condenser 14,an expansion device 16, and an evaporator 18. The heat transfer circuit10 is exemplary and can be modified to include additional components.For example, in an embodiment the heat transfer circuit 10 can includean economizer heat exchanger, one or more flow control devices, areceiver tank, a dryer, a suction-liquid heat exchanger, or the like. Inan embodiment, the heat transfer circuit 10 can include a plurality ofcompressors 12. In an embodiment, the plurality of compressors 12 caninclude compressors having different capacities.

It will be appreciated that the heat transfer circuit 10 can generallybe applied in a variety of systems used, for example, to control anenvironmental condition (e.g., temperature, humidity, air quality, orthe like) in a space (generally referred to as a conditioned space).Examples of systems include, but are not limited to, heating,ventilation, air conditioning and refrigeration (HVACR) systems,transport refrigeration systems, or the like.

The components of the heat transfer circuit 10 are fluidly connected.The heat transfer circuit 10 can be specifically configured to be a typeof cooling system (e.g., fluid chiller) capable of operating in acooling mode. Alternatively, the heat transfer circuit 10 can bespecifically configured to be a heat pump system which can operate inboth a cooling mode and a heating/defrost mode.

Heat transfer circuit 10 operates according to generally knownprinciples. The heat transfer circuit 10 can be configured to use a heattransfer fluid or medium (e.g. working fluid) to heat or cool a processfluid or medium (e.g., a liquid such as, but not limited to, water orthe like), in which case the heat transfer circuit 10, in an embodiment,may be generally representative of a fluid chiller system. The heattransfer circuit 10 can alternatively be configured to use a heattransfer fluid or medium (e.g. working fluid) to heat or cool a processmedium or fluid (e.g., a gas such as, but not limited to, air or thelike), in which case the heat transfer circuit 10 may be generallyrepresentative of an air conditioner or heat pump. In an example, theworking fluid can be a refrigerant or refrigerant blend.

In operation, the compressor 12 compresses a heat transfer fluid orworking fluid (e.g., refrigerant or the like) from a relatively lowerpressure gas to a relatively higher-pressure gas. The relativelyhigher-pressure gas is discharged from the compressor 12 and flowsthrough the condenser 14. In accordance with generally known principles,the heat transfer fluid flows through the condenser 14 and rejects heatto a heat transfer fluid or medium (e.g., water, air, etc.), therebycooling the heat transfer fluid. The cooled heat transfer fluid, whichis now in a liquid form, flows to the expansion device 16. The expansiondevice 16 reduces the pressure of the heat transfer fluid. As a result,a portion of the heat transfer fluid is converted to a gaseous form. Theheat transfer fluid, which is now in a mixed liquid and gaseous formflows to the evaporator 18. The heat transfer fluid flows through theevaporator 18 and absorbs heat from a heat transfer medium (e.g., water,air, etc.), heating the heat transfer fluid, and converting it to agaseous form. The gaseous heat transfer fluid then returns to thecompressor 12. The above-described process continues while the heattransfer circuit is operating, for example, in a cooling mode (e.g.,while the compressor 12 is enabled).

Embodiments disclosed herein generally relate to lubricant blends. Inparticular, compositions, methods, systems, and applications herein aredirected to lubricant blends that balance solubility and viscosity of arefrigerant, where in some cases the lubricant blends herein help reducesolubility of a refrigerant.

Herein “solubility” means how much refrigerant is absorbed into thelubricant, where more refrigerant absorbed by the lubricant blend meansa higher solubility and vice versa.

Herein, “miscibility” means the temperature at which there is a twophase fluid present, where above a certain critical solution temperaturea single phase fluid may be maintained, and where below this certaincritical solution temperature a two phase fluid would be present.

Herein, a lubricant blend's solubility, in particular if it has a highersolubility, and also its miscibility, can impact the lubricant blend'soverall viscosity. The lubricity (e.g. lubrication quality) can beimpacted when the viscosity is too low, for example through insufficientbearing film thickness in the compressor which can lead to system wear,reduced system life, and/or system failure. Too high of viscosity canimpact efficiency of the system through increased power consumption tomove the fluid. Targeting a suitable resulting viscosity from lubricantblend can provide adequate viscosity to create an acceptable film whenmixed with refrigerant, for example in a chiller system. That is, thesolubility of the refrigerant is not detrimental to the viscosity toprovide an acceptable bearing film thickness.

In an embodiment, bearing film thickness can be satisfied by a ratio ofthe viscosity of the lubricant. For example, the ratio is of theviscosity of a particular oil at the operating temperature relative tothe required viscosity needed in the bearing application. This may becalled the viscosity ratio (denoted by a “kappa”). In an embodiment, theratio can be defined as a “kappa value”. In an embodiment, the kappavalue is at or about 2. In an embodiment, a kappa value is at least 2.In an embodiment, the kappa value may be as low as 1, but where in somecircumstances such a low value is a minimum in order to prevent damage.

In an embodiment, a lubricant blend herein includes a mixture of two ormore different types of lubricants to reduce refrigerant solubility, forexample in comparison to a single lubricant of the same or similarviscosity grade, or to other lubricant blends that would not reduce therefrigerant solubility as the lubricant blends described herein.

In an embodiment, the lubricant blend is mixed with a refrigerant orrefrigerant blend.

In an embodiment, the refrigerant or refrigerant blend is a relativelysoluble refrigerant type when mixed with a single lubricant. In anembodiment, the refrigerant or refrigerant blend is a low pressurerefrigerant type, which includes for example an olefin refrigerant type.In an embodiment, the refrigerant or refrigerant blend is a refrigeranttype suitable for use in a chiller, for example a fluid chillerimplemented with a centrifugal compressor.

In an embodiment, the refrigerant or refrigerant blend is a blend of tworefrigerants.

In an embodiment, the refrigerant or refrigerant blend includes a firstrefrigerant at or about 60 to at or about 90 percent by weight and asecond refrigerant at or about 10 to at or about 40 percent by weight.

In an embodiment, the refrigerant or refrigerant blend includes a firstrefrigerant at or about 70 to at or about 90 percent by weight and asecond refrigerant at or about 10 to at or about 30 percent by weight.

In an embodiment, the refrigerant or refrigerant blend includes a firstrefrigerant at or about 80 to at or about 90 percent by weight and asecond refrigerant at or about 10 to at or about 20 percent by weight.

In an embodiment, the refrigerant or refrigerant blend includes a firstrefrigerant at or about 75 percent by weight to at or about 85 percentby weight and a second refrigerant at or about 15 by weight to at orabout 25 percent by weight.

In an embodiment, the refrigerant or refrigerant blend includes a firstrefrigerant at or about 75 percent by weight to at or about 80 percentby weight and a second refrigerant at or about 20 by weight to at orabout 25 percent by weight.

In an embodiment, the refrigerant or refrigerant blend includes a firstrefrigerant at or about 70 percent by weight to at or about 85 percentby weight and a second refrigerant at or about 15 by weight to at orabout 30 percent by weight.

In an embodiment, the refrigerant or refrigerant blend includes a firstrefrigerant at or about 70 percent by weight to at or about 80 percentby weight and a second refrigerant at or about 20 by weight to at orabout 30 percent by weight.

In an embodiment, the refrigerant or refrigerant blend includes a firstrefrigerant at or about 65 percent by weight to at or about 85 percentby weight and a second refrigerant at or about 15 by weight to at orabout 35 percent by weight.

In an embodiment, the refrigerant or refrigerant blend includes a firstrefrigerant at or about 65 percent by weight to at or about 80 percentby weight and a second refrigerant at or about 20 by weight to at orabout 35 percent by weight.

In an embodiment, the lubricant blend includes at or about 80 to at orabout 85 percent by weight of the first lubricant and at or about 15 toat about 20 percent by weight of the second lubricant.

In an embodiment, the lubricant blend includes at or about 85 to at orabout 90 percent by weight of the first lubricant and at or about 10 toat or about 15 percent by weight of the second lubricant.

In an embodiment, the lubricant blend includes at or about 75 to at orabout 80 percent by weight of the first lubricant and at or about 20 toat about 25 percent by weight of the second lubricant.

In an embodiment, the lubricant blend includes at or about 75 to at orabout 90 percent by weight of the first lubricant and at or about 10 toat or about 25 percent by weight of the second lubricant.

In an embodiment, the lubricant blend includes at or about 65 to at orabout 90 percent by weight of the first lubricant and at or about 10 toat or about 35 percent by weight of the second lubricant.

In an embodiment, the lubricant blend includes at or about 60 to at orabout 75 percent by weight of the first lubricant and at or about 25 toat about 40 percent by weight of the second lubricant.

In an embodiment, the lubricant blend includes at or about 65 to at orabout 75 percent by weight of the first lubricant and at or about 25 toat or about 35 percent by weight of the second lubricant.

In an embodiment, the lubricant blend includes at or about 60 to at orabout 70 percent by weight of the first lubricant and at or about 30 toat about 40 percent by weight of the second lubricant.

In an embodiment, the lubricant blend includes at or about 65 to at orabout 70 percent by weight of the first lubricant and at or about 30 toat about 35 percent by weight of the second lubricant.

In an embodiment, the lubricant blend includes at or about 60 to at orabout 65 percent by weight of the first lubricant and at or about 35 toat or about 40 percent by weight of the second lubricant.

In an embodiment, the refrigerant or refrigerant blend includes forexample, a blend of R1336mzz(Z) (i.e.cis-1,1,1,4,4,4-hexafluorobut-2-ene) as the first refrigerant andR1130(E) (i.e. trans-1,2-dichloroethylene) as the second refrigerant.

In an embodiment, the refrigerant iscis-1-chloro-2,3,3,3-tetrafluoropropene (R-1224yd(Z)). In an embodiment,the refrigerant blend includes cis-1-chloro-2,3,3,3-tetrafluoropropene(R-1224yd(Z)).

In an embodiment, reference to percentage by weight, for example, as itapplies to a refrigerant blend that includes R1336mzz(Z) (i.e.cis-1,1,1,4,4,4-hexafluorobut-2-ene) as the first refrigerant andR1130(E) (i.e. trans-1,2-dichloroethylene) as the second refrigerant,can also mean herein a percentage by volume of each of the componentsand may include the above percentages in paragraphs [0043] to [0052].See also paragraphs [0143] to [0163] described below which mentionpercentages by volume.

In an embodiment, the lubricant blend includes a first lubricant and asecond lubricant. In an embodiment, the first lubricant is a baselubricant present in relatively higher percentage by volume of thelubricant blend than the second lubricant. In an embodiment, the secondlubricant is a blend lubricant added to the first lubricant and ispresent in a relatively lower percentage by volume of the lubricantblend than the first lubricant.

In an embodiment, the first lubricant has a higher viscosity than thesecond lubricant.

In an embodiment, the first lubricant has an International StandardsOrganization (ISO) viscosity for example at 40° C. of at or about 120 toat or about 220 cSt.

In an embodiment, the first lubricant has an International StandardsOrganization (ISO) viscosity for example at 40° C. of 170 centistoke(cSt), of about 170 cSt, or up to 170 cSt before being blended with thesecond lubricant. It is appreciated that the viscosity may changedepending on the temperature, and may change +/−10%.

In an embodiment, the second lubricant has an International StandardsOrganization (ISO) viscosity for example at 40° C. of at or about 4 toat or about 30 cSt.

In an embodiment, the second lubricant has an International StandardsOrganization (ISO) viscosity for example at 40° C. of at or about 4 toat or about 20 cSt.

In an embodiment, the second lubricant has an International StandardsOrganization (ISO) viscosity for example at 40° C. of at or about 20 toat or about 30 cSt.

In an embodiment, the second lubricant has an International StandardsOrganization (ISO) viscosity for example at 40° C. of at or about 12 toat or about 30 cSt.

In an embodiment, the second lubricant has an International StandardsOrganization (ISO) viscosity for example at 40° C. of at or about 12 toat or about 20 cSt.

In an embodiment, the second lubricant has an International StandardsOrganization (ISO) viscosity for example at 40° C. of at or about 4 toat or about 12 cSt.

In an embodiment, the second lubricant has an ISO viscosity for exampleat 40° C. of at, about, or up to 4 to 5 cSt before being blended withthe first lubricant.

In an embodiment, the lubricant blend has a resulting ISO viscosity forexample at 40° C. of at or about 32 to at or about 120 cSt.

In an embodiment, lubricant blend has a resulting ISO viscosity forexample at 40° C. of at or about 32 to at or about 70 cSt.

In an embodiment, lubricant blend has a resulting ISO viscosity forexample at 40° C. of at or about 32 to at or about 80 cSt.

In an embodiment, lubricant blend has a resulting ISO viscosity forexample at 40° C. of at or about 32 to at or about 90 cSt.

In an embodiment, lubricant blend has a resulting ISO viscosity forexample at 40° C. of at or about 32 to at or about 75 cSt.

In an embodiment, lubricant blend has a resulting ISO viscosity forexample at 40° C. of at or about 32 to at or about 85 cSt.

In an embodiment, lubricant blend has a resulting ISO viscosity forexample at 40° C. of at or about 32 to at or about 73 cSt.

In an embodiment, lubricant blend has a resulting ISO viscosity forexample at 40° C. of at or about 90 to at or about 120 cSt.

In an embodiment, lubricant blend has a resulting ISO viscosity forexample at 40° C. of at or about 80 to at or about 120 cSt.

In an embodiment, lubricant blend has a resulting ISO viscosity forexample at 40° C. of at or about 70 to at or about 120 cSt.

In an embodiment, lubricant blend has a resulting ISO viscosity forexample at 40° C. of at or about 85 to at or about 120 cSt.

In an embodiment, lubricant blend has a resulting ISO viscosity forexample at 40° C. of at or about 75 to at or about 120 cSt.

In an embodiment, lubricant blend has a resulting ISO viscosity forexample at 40° C. of at or about 73 to at or about 120 cSt.

In an embodiment, lubricant blend has a resulting ISO viscosity forexample at 40° C. of at or about 68 to at or about 120 cSt.

In an embodiment, lubricant blend has a resulting ISO viscosity forexample at 40° C. of at or about 80 to at or about 90 cSt.

In an embodiment, lubricant blend has a resulting ISO viscosity forexample at 40° C. of at or about 85 to at or about 90 cSt.

In an embodiment, lubricant blend has a resulting ISO viscosity forexample at 40° C. of at or about 70 to at or about 90 cSt.

In an embodiment, lubricant blend has a resulting ISO viscosity forexample at 40° C. of at or about 75 to at or about 90 cSt.

In an embodiment, lubricant blend has a resulting ISO viscosity forexample at 40° C. of at or about 73 to at or about 90 cSt.

In an embodiment, lubricant blend has a resulting ISO viscosity forexample at 40° C. of at or about 68 to at or about 90 cSt.

In an embodiment, lubricant blend has a resulting ISO viscosity forexample at 40° C. of at or about 32 to at or about 90 cSt.

In an embodiment, lubricant blend has a resulting ISO viscosity forexample at 40° C. of at or about 80 to at or about 85 cSt.

In an embodiment, lubricant blend has a resulting ISO viscosity forexample at 40° C. of at or about 75 to at or about 85 cSt.

In an embodiment, lubricant blend has a resulting ISO viscosity forexample at 40° C. of at or about 73 to at or about 85 cSt.

In an embodiment, lubricant blend has a resulting ISO viscosity forexample at 40° C. of at or about 70 to at or about 85 cSt.

In an embodiment, lubricant blend has a resulting ISO viscosity forexample at 40° C. of at or about 68 to at or about 85 cSt.

In an embodiment, lubricant blend has a resulting ISO viscosity forexample at 40° C. of at or about 32 to at or about 85 cSt.

In an embodiment, lubricant blend has a resulting ISO viscosity forexample at 40° C. of at or about 75 to at or about 80 cSt.

In an embodiment, lubricant blend has a resulting ISO viscosity forexample at 40° C. of at or about 73 to at or about 80 cSt.

In an embodiment, lubricant blend has a resulting ISO viscosity forexample at 40° C. of at or about 70 to at or about 80 cSt.

In an embodiment, lubricant blend has a resulting ISO viscosity forexample at 40° C. of at or about 68 to at or about 80 cSt.

In an embodiment, lubricant blend has a resulting ISO viscosity forexample at 40° C. of at or about 32 to at or about 80 cSt.

In an embodiment, lubricant blend has a resulting ISO viscosity forexample at 40° C. of at or about 73 to at or about 75 cSt.

In an embodiment, lubricant blend has a resulting ISO viscosity forexample at 40° C. of at or about 70 to at or about 75 cSt.

In an embodiment, lubricant blend has a resulting ISO viscosity forexample at 40° C. of at or about 68 to at or about 75 cSt.

In an embodiment, lubricant blend has a resulting ISO viscosity forexample at 40° C. of at or about 32 to at or about 75 cSt.

In an embodiment, the lubricant blend has a resulting ISO viscosity forexample at 40° C. of at or about 60 to at or about 120 cSt.

In an embodiment, lubricant blend has a resulting ISO viscosity forexample at 40° C. of at or about 70 to at or about 120 cSt.

In an embodiment, the lubricant blend has a resulting ISO viscosity forexample at 40° C. of at or about 60 to at or about 70 cSt.

In an embodiment, lubricant blend has a resulting ISO viscosity forexample at 40° C. of at or about 68 to at or about 70 cSt.

In an embodiment, lubricant blend has a resulting ISO viscosity forexample at 40° C. of at or about 32 cSt. In an embodiment, the lubricantblend is used in a system implemented with rotary, screw, or scrollcompressor.

In an embodiment, lubricant blend has a resulting ISO viscosity forexample at 40° C. of at or about 68 cSt to at or about 73 cSt. In anembodiment, the lubricant blend is used in a system implemented with acentrifugal compressor, which may operate at variable speed.

In an embodiment, lubricant blend has a resulting ISO viscosity forexample at 40° C. of at or about 120 cSt. In an embodiment, thelubricant blend is used in a system implemented in a variable speedapplication.

In an embodiment, the second lubricant reduces the solubility of therefrigerant or refrigerant blend when mixed with the lubricant blend.

In an embodiment, the lubricant blend includes one or more of POE, PVE,and PAG as the first lubricant and one or more of alkylbenzene (AB),polyalphaolefin (PAO), mineral oil, and estolide.

In an embodiment, the lubricant blend includes by volume of thelubricant blend at or about 60 to at or about 90 percent by volume ofthe first lubricant and at or about 10 to at or about 40 percent byvolume of the second lubricant.

In an embodiment, the lubricant blend includes by volume of thelubricant blend at or about 60 to at or about 85 percent by volume ofthe first lubricant and at or about 15 to at or about 40 percent byvolume of the second lubricant.

In an embodiment, the lubricant blend includes by volume of thelubricant blend at or about 60 to at or about 80 percent by volume ofthe first lubricant and at or about 20 to at or about 40 percent byvolume of the second lubricant.

In an embodiment, the lubricant blend includes by volume of thelubricant blend at or about 60 to at or about 75 percent by volume ofthe first lubricant and at or about 25 to at or about 40 percent byvolume of the second lubricant.

In an embodiment, the lubricant blend includes by volume of thelubricant blend at or about 60 to at or about 70 percent by volume ofthe first lubricant and at or about 30 to at or about 40 percent byvolume of the second lubricant.

In an embodiment, the lubricant blend includes by volume of thelubricant blend at or about 60 to at or about 65 percent by volume ofthe first lubricant and at or about 35 to at or about 40 percent byvolume of the second lubricant.

In an embodiment, the lubricant blend includes by volume of thelubricant blend at or about 65 to at or about 90 percent by volume ofthe first lubricant and at or about 10 to at or about 35 percent byvolume of the second lubricant.

In an embodiment, the lubricant blend includes by volume of thelubricant blend at or about 65 to at or about 85 percent by volume ofthe first lubricant and at or about 15 to at or about 35 percent byvolume of the second lubricant.

In an embodiment, the lubricant blend includes by volume of thelubricant blend at or about 65 to at or about 80 percent by volume ofthe first lubricant and at or about 20 to at or about 35 percent byvolume of the second lubricant.

In an embodiment, the lubricant blend includes by volume of thelubricant blend at or about 65 to at or about 75 percent by volume ofthe first lubricant and at or about 25 to at or about 35 percent byvolume of the second lubricant.

In an embodiment, the lubricant blend includes by volume of thelubricant blend at or about 65 to at or about 70 percent by volume ofthe first lubricant and at or about 30 to at or about 35 percent byvolume of the second lubricant.

In an embodiment, the lubricant blend includes by volume of thelubricant blend at or about 70 to at or about 90 percent by volume ofthe first lubricant and at or about 10 to at or about 30 percent byvolume of the second lubricant.

In an embodiment, the lubricant blend includes by volume of thelubricant blend at or about 70 to at or about 85 percent by volume ofthe first lubricant and at or about 15 to at or about 30 percent byvolume of the second lubricant.

In an embodiment, the lubricant blend includes by volume of thelubricant blend at or about 70 to at or about 80 percent by volume ofthe first lubricant and at or about 20 to at or about 30 percent byvolume of the second lubricant.

In an embodiment, the lubricant blend includes by volume of thelubricant blend at or about 70 to at or about 75 percent by volume ofthe first lubricant and at or about 25 to at or about 30 percent byvolume of the second lubricant.

In an embodiment, the lubricant blend includes by volume of thelubricant blend at or about 75 to at or about 90 percent by volume ofthe first lubricant and at or about 10 to at or about 25 percent byvolume of the second lubricant.

In an embodiment, the lubricant blend includes by volume of thelubricant blend at or about 75 to at or about 85 percent by volume ofthe first lubricant and at or about 15 to at or about 25 percent byvolume of the second lubricant.

In an embodiment, the lubricant blend includes by volume of thelubricant blend at or about 75 to at or about 80 percent by volume ofthe first lubricant and at or about 20 to at or about 25 percent byvolume of the second lubricant.

In an embodiment, the lubricant blend includes by volume of thelubricant blend at or about 80 to at or about 90 percent by volume ofthe first lubricant and at or about 10 to at or about 20 percent byvolume of the second lubricant.

In an embodiment, the lubricant blend includes by volume of thelubricant blend at or about 80 to at or about 85 percent by volume ofthe first lubricant and at or about 15 to at or about 20 percent byvolume of the second lubricant.

In an embodiment, the lubricant blend includes by volume of thelubricant blend at or about 85 to at or about 90 percent by volume ofthe first lubricant and at or about 10 to at or about 15 percent byvolume of the second lubricant.

In an embodiment, the refrigerant or refrigerant blend includes byvolume of the refrigerant or refrigerant blend at or about 60 to at orabout 90 percent by volume of a first refrigerant and at or about 10 toat or about 40 percent by volume of a second refrigerant.

In an embodiment, the refrigerant or refrigerant blend includes byvolume of the refrigerant or refrigerant blend at or about 60 to at orabout 85 percent by volume of the first refrigerant and at or about 15to at or about 40 percent by volume of the second refrigerant.

In an embodiment, the refrigerant or refrigerant blend includes byvolume of the refrigerant or refrigerant blend at or about 60 to at orabout 80 percent by volume of the first refrigerant and at or about 20to at or about 40 percent by volume of the second refrigerant.

In an embodiment, the refrigerant or refrigerant blend includes byvolume of the refrigerant or refrigerant blend at or about 60 to at orabout 75 percent by volume of the first refrigerant and at or about 25to at or about 40 percent by volume of the second refrigerant.

In an embodiment, the refrigerant or refrigerant blend includes byvolume of the refrigerant or refrigerant blend at or about 60 to at orabout 70 percent by volume of the first refrigerant and at or about 30to at or about 40 percent by volume of the second refrigerant.

In an embodiment, the refrigerant or refrigerant blend includes byvolume of the refrigerant or refrigerant blend at or about 60 to at orabout 65 percent by volume of the first refrigerant and at or about 35to at or about 40 percent by volume of the second refrigerant.

In an embodiment, the refrigerant or refrigerant blend includes byvolume of the refrigerant or refrigerant blend at or about 65 to at orabout 90 percent by volume of the first refrigerant and at or about 10to at or about 35 percent by volume of the second refrigerant.

In an embodiment, the refrigerant or refrigerant blend includes byvolume of the refrigerant or refrigerant blend at or about 65 to at orabout 85 percent by volume of the first refrigerant and at or about 15to at or about 35 percent by volume of the second refrigerant.

In an embodiment, the refrigerant or refrigerant blend includes byvolume of the refrigerant or refrigerant blend at or about 65 to at orabout 80 percent by volume of the first refrigerant and at or about 20to at or about 35 percent by volume of the second refrigerant.

In an embodiment, the refrigerant or refrigerant blend includes byvolume of the refrigerant or refrigerant blend at or about 65 to at orabout 75 percent by volume of the first refrigerant and at or about 25to at or about 35 percent by volume of the second refrigerant.

In an embodiment, the refrigerant or refrigerant blend includes byvolume of the refrigerant or refrigerant blend at or about 65 to at orabout 70 percent by volume of the first refrigerant and at or about 30to at or about 35 percent by volume of the second refrigerant.

In an embodiment, the refrigerant or refrigerant blend includes byvolume of the refrigerant or refrigerant blend at or about 70 to at orabout 90 percent by volume of the first refrigerant and at or about 10to at or about 30 percent by volume of the second refrigerant.

In an embodiment, the refrigerant or refrigerant blend includes byvolume of the refrigerant or refrigerant blend at or about 70 to at orabout 85 percent by volume of the first refrigerant and at or about 15to at or about 30 percent by volume of the second refrigerant.

In an embodiment, the refrigerant or refrigerant blend includes byvolume of the refrigerant or refrigerant blend at or about 70 to at orabout 80 percent by volume of the first refrigerant and at or about 20to at or about 30 percent by volume of the second refrigerant.

In an embodiment, the refrigerant or refrigerant blend includes byvolume of the refrigerant or refrigerant blend at or about 70 to at orabout 75 percent by volume of the first refrigerant and at or about 25to at or about 30 percent by volume of the second refrigerant.

In an embodiment, the refrigerant or refrigerant blend includes byvolume of the refrigerant or refrigerant blend at or about 75 to at orabout 90 percent by volume of the first refrigerant and at or about 10to at or about 25 percent by volume of the second refrigerant.

In an embodiment, the refrigerant or refrigerant blend includes byvolume of the refrigerant or refrigerant blend at or about 75 to at orabout 85 percent by volume of the first refrigerant and at or about 15to at or about 25 percent by volume of the second refrigerant.

In an embodiment, the refrigerant or refrigerant blend includes byvolume of the refrigerant or refrigerant blend at or about 75 to at orabout 80 percent by volume of the first refrigerant and at or about 20to at or about 25 percent by volume of the second refrigerant.

In an embodiment, the refrigerant or refrigerant blend includes byvolume of the refrigerant or refrigerant blend at or about 80 to at orabout 90 percent by volume of the first refrigerant and at or about 10to at or about 20 percent by volume of the second refrigerant.

In an embodiment, the refrigerant or refrigerant blend includes byvolume of the refrigerant or refrigerant blend at or about 80 to at orabout 85 percent by volume of the first refrigerant and at or about 15to at or about 20 percent by volume of the second refrigerant.

In an embodiment, the refrigerant or refrigerant blend includes byvolume of the refrigerant or refrigerant blend at or about 85 to at orabout 90 percent by volume of the first refrigerant and at or about 10to at or about 15 percent by volume of the second refrigerant.

In an embodiment, the first lubricant is POE or PVE and the secondlubricant is AB or mineral oil.

In an embodiment, the first lubricant is POE and the second lubricant isAB.

In an embodiment, reference to percentage by volume, for example, as itapplies to a lubricant blend that includes POE or PVE as the firstlubricant and AB or mineral as the second lubricant, can also meanpercentage by weight of each of the components and may include the abovepercentages in paragraphs [0122] to [0142].

It will be appreciated that any of the lubricant blends described abovein paragraphs [0122] to [142] may be combined with any of therefrigerant/refrigerant blends described above in paragraphs [0143] to[0163], for example to obtain a desired viscosity in accordance withparagraphs [0068] to [0119] above and also to obtain a desiredsolubility and miscibility.

In an embodiment, the amount of the first lubricant and the amount ofthe second lubricant may be selected based on factors including one ormore of its miscibility, solubility with the refrigerant or refrigerantblend, and resulting viscosity, and combinations thereof. In anembodiment, the selection of the amount of the first and secondlubricants is based on a balance of these factors.

In an embodiment, a POE includes but is not limited to for example acompound which may be derived from alcohols including pentaerythritol,trimethylolpropane, neopentyl glycol, and dipentaerythritol (orcombinations), and carboxylic acids comprised of 4 to 10 carbons inlinear or branched formation or mixed (both linear and branched).

In an embodiment, a PVE includes but is not limited to for examplepolymers that contain ether side chains comprised of 2-8 carbons.

In an embodiment, a PAG includes but is not limited to for examplepolymers derived from propylene oxide or a mixture of propylene oxideand ethylene oxide; PAGs may be uncapped, mono-end-capped, ordouble-end-capped.

In an embodiment, an AB includes but is not limited to for examplealkylbenzenes which are branched, linear, or are combinations thereof.

In an embodiment, a PAO includes but is not limited to for exampleoligomers of linear alpha-olefins.

In an embodiment, a mineral oil (MO) includes but is not limited to forexample paraffins, naphthenes, aromatics, nonhydrocarbons, orcombinations thereof.

In an embodiment, systems which implement the lubricant blends hereinand the refrigerant or refrigerant blends herein can include at or aboutthree pounds (3 lbs.) charge of refrigerant for example per ton ofsystem cooling capacity. In some single compressor systems, such as forexample systems with a centrifugal compressor, the cooling capacity intons can range from at or about 200 to at or about 1800 tons of cooling,which may be at or about 600 to at or about 5400 lbs. of refrigerant. Inan embodiment, the lubricant blend charge can be at or about 75 lbs.

In an embodiment, the lubricant blend can include or be mixed with orwithout additives. In an embodiment, the additives can include one ormore of dispersants, detergents, anti-wear additives, pressure agents,corrosion inhibitors, antioxidants, acid catchers, viscosity indeximprovers, pour point depressants, foaming agents, anti-foaming agents,or other like stabilizing or performance enhancing compounds.

In an embodiment, lubricant blends herein can generally serve as analternative to relatively higher viscosity lubricants to minimizerefrigerant solubility and consequent viscosity reductions.

In an embodiment, lubricant blends herein can improve system efficiencyand can reduce or eliminate the need for additional hardware, such asfor example lubricant separators, and can improve the sustainability ofthe lubricant.

Refrigerants used today and being developed as next generationrefrigerants for stationary HVACR equipment are soluble in POE and PVElubricants, for example in the range of 32 to 120 centistoke (cSt)viscosities, depending on the operation type of the HVACR equipment(e.g. variable or fixed speed operation, compressor type e.g., rotary,screw, centrifugal, and the like). However, refrigerants used today andnewer developed refrigerants can potentially exhibit higher solubilityand may be increasingly used in variable or high speed compressorproduct applications. Application of lubricant blends in HVACRcompressors, as an alternative to historically used single lubricanttypes in higher viscosity grades, provides more flexibility in alteringthe refrigerant solubility characteristics due to the inherentlydifferent physical and chemical properties of different types oflubricants.

By lowering the refrigerant solubility, a lower lubricant viscositygrade could be effectively applied and would provide the followingadvantages: 1) higher system efficiency due to lower power consumption(e.g. in comparison to using a single lubricant type at a higherviscosity); 2) elimination of the need for additional hardware such asoil separators and heaters; and/or 3) improved sustainability of thelubricant (depending on the lubricant selected for mixing). For example,estolides and polyol esters (POEs) exhibit higher biodegradability asopposed to conventional mineral oil or alkylbenzene type oils forexample as per the Organization for Economic Co-operation andDevelopment (OECD) 301. Also, life cycle assessments have suggestedlower greenhouse gas use.

Lubricant blends of interest include 1) polyol ester (POE) lubricantsmixed with one or more lubricants of type alkylbenzene (AB), mineraloil, polyalphaolefin (PAO), polyalkylene glycol (PAG), polyvinyl ether(PVE), and estolide, or 2) polyvinyl ether mixed with one or morelubricants of type AB, mineral oil, PAO, PAG, POE, and estolide.

AB, mineral oil, PAO, and estolide are soluble in POE and PVE, but alonemay have inadequate miscibility and/or solubility with hydrofluorocarbonand olefin refrigerants.

In an embodiment, the first lubricant is POE and/or PVE and the secondlubricant is estolide.

Applications of the lubricant blends herein can include vaporcompression systems that employ a centrifugal compressor, a screwcompressor, a scroll compressor, or reciprocating compressor, which maybe used in a fixed or variable speed operation. The lubricant blendsherein may be mixed with a refrigerant or refrigerant blend, includingtwo or more of saturated hydrofluorocarbon, unsaturatedhydrofluorocarbon, saturated hydrofluorochlorocarbon, unsaturatedhydrofluorochlorocarbon, hydrocarbon, fluorinated or nonfluorinatedether, carbon dioxide, and ammonia.

In an embodiment, such refrigerants can include but are not limited toat least one of or blends of 1,1-dichloro-2,2,2-difluoroethane,1,1,1,2-tetrafluoroethane, 1,1,1,3,3-pentafluoropropane,1,1,2,2,3-pentafluoropropane, difluoromethane, 1,1-difluoroethane,1-chloro-3,3,3-trifluoropropene (Z), 2-chloro-3,3,3-trifluoropropene,1,1-dichloro-3,3,3-trifluoropropene, 2,3,3,3-tetrafluoropropene,1,3,3,3-tetrafluoropropene (E), 1,3,3,3-tetrafluoropropene (Z),1,2-dichloro-3,3,3-trifluoropropene (E),1,2-dichloro-3,3,3-trifluoropropene (Z),1,1,3-trichloro-3,3,3-trifluoropropene, 1,2-dichloroethylene (E),1,2-dichloroethylene (Z), 1,1-dichloroethylene,1,1,1,4,4,4-hexafluorobutene (Z), 1,1,1,4,4,4-hexafluorobutene (E),1,1,1,2,3-pentafluoropropane, 1,1,1,3,3-pentafluoropropane, C2-C8hydrocarbons, carbon dioxide, and ammonia, and combinations thereof.

Example-Development of Lubricant Blend for the refrigerant blend of 75%by weight of R-1336mzz(Z)—a fluorinated molecule—and 25% by weight ofR-1130(E)—a chlorinated molecule (hereafter “example refrigerant blend”or ER-10 in the Figures).

Table 1 shows a refrigerant blend comprised of approximately 75% byweight R-1336mzz(Z)—a fluorinated molecule—and approximately 25% byweight R-1130(E)—a chlorinated molecule. In the HVACR industry,chlorine-containing refrigerants such as R-11, R-12, and R-123 (allsingle-component refrigerants) are physically compatible or misciblewith, and are typically applied with mineral oil lubricants. Althoughthese refrigerants are miscible with other lubricant types, mineral oillubricants have exhibited favorable commercial and performancecharacteristics that have sustained their selection and application.Mineral oil lubricants have been used in applications with R-123, ahydrochlorofluorocarbon (HCFC) refrigerant used in HVACR systems, inwhich the example refrigerant blend may be implemented. R-123 and otherHCFC refrigerants are being or will be phased out of production and useper requirements of the Montreal Protocol and regulatory policies, andthe example refrigerant blend is a proposed R-123 alternative.

TABLE 1 Approximate Nominal Component Purpose Concentration

Blend Component 75%

Blend Component 25%

During initial studies of the example refrigerant blend, the physicalcompatibility (miscibility) of a tested mineral oil and the examplerefrigerant blend was evaluated. As shown in FIG. 2, the examplerefrigerant blend had insufficient miscibility with the tested mineraloil, as two distinct phases—a “refrigerant-rich phase” 20 and a“lubricant-rich phase” 22—were formed at room temperature. For theintended applications, it may be desired that, in an embodiment, therefrigerant and lubricant maintain one single phase throughout theoperating range and ambient temperature exposures. For example, suchrange includes at or about −12° C. to at or about 60° C. Thus, thetested mineral oil was ruled out as a viable single lubricant option forthe example refrigerant blend. It will be appreciated that the testedmineral oil, or other mineral oils, may be used as a potential blendcomponent in other lubricant blend selections.

FIG. 2 shows a glass tube at ambient conditions (˜20° C.) containing 95%by weight of the example refrigerant blend and 5% by weight mineral oil.Two separate phases formed, demonstrating insufficient miscibilitybetween the example refrigerant blend and mineral oil.

In general, hydrofluorocarbon (HFC) refrigerants that have no chlorinepresent in the molecules, such as R-134a, R-410A, and R-245fa, are notphysically compatible with mineral oil lubricants and instead areapplied with compatible synthetic lubricants such as polyol ester (POE)or polyvinyl ether (PVE). After the tested mineral oil was found to bephysically incompatible with the example refrigerant blend, twocommercially available synthetic lubricants (a POE and a PVE) wereselected for further study. Miscibility studies were conducted with bothof these lubricants and both maintained a single phase with the examplerefrigerant blend throughout the entire temperature range of interest.

Miscibility-Miscibility testing may be used as a screening tool duringlubricant selection activities. If the miscibility is determined to beacceptable, then additional studies are conducted to evaluate thesolubility and viscosity of the refrigerant/lubricant mixture. Ingeneral, sufficient miscibility of the lubricant with the refrigerantensures proper oil return to the compressor and minimizes negativeimpact of a separate oil phase on other components of the system, forexample heat exchanger devices in the system, while at the same timelimited solubility of the refrigerant in the lubricant can avoidexcessive lubricant viscosity reduction in the compressor.

Solubility and viscosity of a refrigerant/lubricant mixture aredetermined from plots shown in FIGS. 3 and 4, which arePressure/Viscosity/Temperature (PVT) charts. Data from a newrefrigerant/lubricant pair are compared to data for the currentrefrigerant/lubricant pair at similar conditions. The higher thesolubility, or the more refrigerant that dissolves in the lubricant, themore the viscosity will be reduced. If the viscosity reduction isexcessive, bearing reliability and compressor life can be negativelyimpacted.

With the example refrigerant blend/POE #1 mixture, refrigerantsolubility was significantly increased in comparison to the mixtureproperties of R-123/mineral oil. Areas of the chiller operating map thathad a solubility of 20% R-123 refrigerant in mineral oil would beexceeding 30% refrigerant solubility for the example refrigerant blendin POE #1 oil. At standard cooling conditions, refrigerant solubilitythat typically was around 4% with mineral oil would now exceed 10% withthe example refrigerant blend/POE #1 mixture. Standard coolingconditions can include for example 40° F. or 4.4° C. In other examples,cooling conditions can include specific conditions as designed byrequest e.g. at 60° F. or 15.6° C. and/or at 80° F. or 26.7° C.

FIGS. 3 and 4 show viscosity relative to pressure and temperature. FIG.6 shows solubility percentage with respect to temperature and pressure.

FIG. 6 is a chart showing refrigerant solubility of the examplerefrigerant blend with a lubricant blend herein in comparison to theexample refrigerant blend with the POE #1 and relative to R123/mineraloil. The percentage solubility is shown as a function of increasing oiltemperature and increasing refrigerant saturated temperature. Each linerepresents a percentage solubility of the refrigerant in therefrigerant/oil mixture dependent upon the oil temperature andrefrigerant saturated temperature.

As shown in FIG. 3, a mixture viscosity of the example refrigerantblend/POE #1 is reduced relative to R-123/mineral oil due to higherrefrigerant solubility of the example refrigerant blend in POE #1. FIG.3 shows mixture viscosity comparisons for three different saturatedrefrigerant conditions.

Lower mixture viscosities in general are not detrimental for anapplication and in some scenarios are beneficial; however, a certainmixture viscosity is desired to maintain a sufficient film thickness atthe bearings. In FIG. 3, the mixture viscosity for the examplerefrigerant blend/POE #1 fell below minimum requirements in someconditions.

Lubricant blends compositions herein, including the example, canminimize lubrication system design changes, e.g. adding heaters to theoil tank to lower refrigerant concentrations, changing control setpoints to limit the chiller operating map, and/or adding oil separatortechnologies to separate the dissolved refrigerant from the lubricant.

Solubility, viscosity, and miscibility requirements were developed toguide the lubricant selection and development process, based off ofsuccessful application experiences with R-123 and mineral oil.

POE-based lubricants that exhibit low refrigerant solubility wereevaluated. In an embodiment, the refrigerant is an HFC refrigerant type.Such POE lubricants were evaluated for whether lower solubility of theexample refrigerant blend would be observed, while also maintaining adesired miscibility. Such POE-based lubricants may also be commerciallyavailable. A POE lubricant (POE #2) (with a relatively higher molecularweight) that was expected to have low solubility with the examplerefrigerant blend was tested. The results of the PVT chart demonstratedthat POE #2 has favorable solubility improvements with the examplerefrigerant blend, but exhibited insufficient miscibility. As shown inTable 2, at the 10% by weight lubricant concentration (with 90% percentby weight of the example refrigerant blend), two phases were observed at6° C., whereas the miscibility requirement was to maintain a singlephase at or below −12° C. These results confirmed that although therefrigerant solubility was reduced with POE #2, the miscibility was alsoreduced. POE #2 did not meet the desired miscibility for the examplerefrigerant blend.

In an embodiment, reference to percent by weight of the lubricant andrefrigerant can also mean percentage by volume of each of the lubricantblend and the refrigerant/refrigerant blend.

In an embodiment, the relative amount of each of the lubricant and therefrigerant may vary including at or about 5%, at or about 10%, at orabout 20%, at or about 30%, and at or about 50%. In an embodiment, anyof these percentages can appropriately make up a lower limit or upperlimit. In an embodiment, the relative amount of lubricant andrefrigerant can consider the type of system in which it is implemented,for example a HVACR system, such as but not limited to for example afluid chiller, and which may use a certain compressor, for example butnot limited to a centrifugal compressor.

TABLE 2 Miscibility Results for the example refrigerant blend and POE #2Temperature % Lubricant ° C. ° F. 50% 10% 60 140 Clear, Single PhaseClear, Single Phase 40 104 Clear, Single Phase Clear, Single Phase 20 68Clear, Single Phase Clear, Single Phase 15 59 Clear, Single Phase Clear,Single Phase 14 57 Clear, Single Phase Clear, Single Phase 13 55 Clear,Single Phase Clear, Single Phase 12 54 Clear, Single Phase Clear, SinglePhase 11 52 Clear, Single Phase Clear, Single Phase 10 50 Clear, SinglePhase Clear, Single Phase 9 48 Clear, Single Phase Clear, Single Phase 846 Clear, Single Phase Clear, Single Phase 7 45 Clear, Single PhaseHazy, Single Phase 6 43 Clear, Single Phase Hazy, Two Phases 5 41 Clear,Single Phase Hazy, Two Phases 0 32 Clear, Single Phase Hazy, Two Phases−4 25 Clear, Single Phase Clear, Two Phases −5 23 Clear, Single PhaseClear, Two Phases −10 14 Clear, Single Phase Clear, Two Phases −11 12Clear, Single Phase Clear, Two Phases −12 10 Clear, Single Phase Clear,Two Phases −13 9 Clear, Single Phase Clear, Two Phases −14 7 Clear,Single Phase Clear, Two Phases −15 5 Clear, Single Phase Clear, TwoPhases −20 −4 Clear, Single Phase Clear, Two Phases

After the miscibility tests with POE #2 revealed that POE #2 did nothave the desired miscibility, e.g. physical compatibility, with theexample refrigerant blend in the temperature range of interest, twoother commercially available low-solubility POEs (POE #3 and POE #4)were evaluated. The POE #3 and POE #4 were evaluated for whethersuitable solubility reductions could be obtained, but that would alsoexhibit better miscibility performance than POE #2 had with the examplerefrigerant blend. Blends of other lubricant types with POE #3 and POE#4 were also evaluated as potential options to reduce or minimize therefrigerant solubility, while maintaining the miscibility and viscosityrequirements.

Results of miscibility screening tests are shown in Table 3. Oil #7 andOil #10 were observed to not have the desired miscibility with theexample refrigerant blend, but the remaining blend options all met thedesired miscibility. Oil #9 was selected for the further reporteddevelopment. Oil #9 had favorable thermal and chemical stability.

TABLE 3 Miscibility Screening Test Results of POE and POE BlendedLubricants Critical Solution Lubricant Temperature IdentifierComposition ° C. ° F. Oil #5 POE #3/POE Blend (of −35 −31 lower relativeviscosity) Oil #6 POE #3/AB Blend −25 −13 Oil #7 POE #3/PAO Blend −5 23Oil #8 POE #3/MO Blend −20 −4 Oil #9 POE #4/AB Blend −20 −4 Oil #10 POE#4/PAO Blend −5 23 Oil #11 POE #4/MO Blend −15 5 POE is polyol ester, ABis alkylbenzene, PAO is polyalphaolefin, and MO is mineral oil.

Table 3 shows an initial miscibility screening test done at onelubricant concentration (10% by weight) with 90% by weight of theexample refrigerant blend. The lubricant blend (composition) included ator about 80% by volume of the identified POE and at or about 20% byvolume of the second lubricant (e.g. AB, PAO, MO). Table 4 shows a morecomprehensive miscibility test of the example refrigerant blend and Oil#9, which was conducted to observe whether the mixture remained in asingle phase at or below −12° C. throughout a range of lubricantconcentrations from 5% to 50% by weight of the mixture of the lubricantand the example refrigerant blend. As shown in Table 4, the 20% byweight lubricant sample exhibited immiscibility (two phases) at −15° C.,whereas all the other concentrations maintained a single phase below−15° C. Thus, the desired miscibility was met.

TABLE 4 Miscibility Test Results of the example refrigerant blend andOil #9 Temper- ature % Lubricant ° C. ° F. 5% 10% 20% 30% 50% 60 140Clear, Clear, Clear, Clear, Clear, Single Single Single Single SinglePhase Phase Phase Phase Phase 50 122 Clear, Clear, Clear, Clear, Clear,Single Single Single Single Single Phase Phase Phase Phase Phase 40 104Clear, Clear, Clear, Clear, Clear, Single Single Single Single SinglePhase Phase Phase Phase Phase 30 86 Clear, Clear, Clear, Clear, Clear,Single Single Single Single Single Phase Phase Phase Phase Phase 20 68Clear, Clear, Clear, Clear, Clear, Single Single Single Single SinglePhase Phase Phase Phase Phase 10 50 Clear, Clear, Clear, Clear, Clear,Single Single Single Single Single Phase Phase Phase Phase Phase 0 32Clear, Clear, Clear, Clear, Clear, Single Single Single Single SinglePhase Phase Phase Phase Phase −5 23 Clear, Clear, Clear, Clear, Clear,Single Single Single Single Single Phase Phase Phase Phase Phase −10 14Clear, Clear, Clear, Clear, Clear, Single Single Single Single SinglePhase Phase Phase Phase Phase −11 12 Clear, Clear, Clear, Clear, Clear,Single Single Single Single Single Phase Phase Phase Phase Phase −12 10Clear, Clear, Clear, Clear, Clear, Single Single Single Single SinglePhase Phase Phase Phase Phase −13 9 Clear, Clear, Hazy, Clear, Clear,Single Single Single Single Single Phase Phase Phase Phase Phase −14 7Clear, Clear, Hazy, Clear, Clear, Single Single Single Single SinglePhase Phase Phase Phase Phase −15 5 Clear, Clear, Hazy, Two Clear,Clear, Single Single Phases Single Single Phase Phase Phase Phase −16 3Clear, Clear, Hazy, Two Hazy, Clear, Single Single Phases Single SinglePhase Phase Phase Phase −17 1 Clear, Clear, Clear, Two Clear, Two Clear,Single Single Phases Phases Single Phase Phase Phase −18 0 Clear, Clear,Clear, Two Clear, Two Clear, Single Single Phases Phases Single PhasePhase Phase −19 −2 Clear, Clear, Clear, Two Clear, Two Clear, SingleSingle Phases Phases Single Phase Phase Phase −20 −4 Clear, Hazy, TwoClear, Two Clear, Two Clear, Single Phases Phases Phases Single PhasePhase −21 −6 Clear, Hazy, Two Clear, Two Clear, Two Clear, Single PhasesPhases Phases Single Phase Phase −22 −8 Clear, Hazy, Two Clear, TwoClear, Two Clear, Single Phases Phases Phases Single Phase Phase

PVT test results of the example refrigerant blend/Oil #9 showed asignificant improvement in solubility characteristics over the examplerefrigerant blend with POE #1.

In addition, mixture viscosity of the example refrigerant blend/Oil #9was an overall improvement in comparison to the example refrigerantblend/POE #1 (FIG. 3). The improvement can be attributed to the lowerrefrigerant solubility of the lubricant blend. See FIG. 4. FIG. 4 showsa plot of oil/refrigerant mixture viscosity, a comparison of the examplerefrigerant blend/POE #1 and relative to Oil #9.

The lubricant blends herein can provide the following advantagesincluding but not limited to avoiding additional hardware, avoidinglimiting the operating map in a new design or a retrofit system, e.g.R-123 systems; and providing a cost effective approach for a lubricantused in HVAC applications.

With further reference to miscibility, in particular the miscibility ofthe lubricant blends from the Example, in general, the lubricant blendsherein would exhibit a desired miscibility with the refrigerant toensure proper oil return to the compressor and minimize situations ofseparate fluid phases which may have a negative impact for example onheat exchanger devices in the system. The lubricant blends herein alsohave limited solubility of the refrigerant to avoid excessive lubricantviscosity reduction in the compressor.

Generally refrigerant/lubricant solutions are partially miscible, ormiscible to a limited extent depending on temperature and fluidconcentrations. Above the critical solution temperature (CST) orconsolute temperature, many refrigerant/lubricant mixtures arecompletely miscible (i.e., single phase). Below the CST, however, theliquid separates into two phases. This does not mean that the lubricantand refrigerant are insoluble in each other. The two liquid phases aresolutions; one is lubricant-rich and the other refrigerant-rich (seee.g. FIG. 2). The CST changes as refrigerant and lubricantconcentrations vary (see e.g. FIG. 5). Generally, desired miscibilitycan be set at the highest temperature and corresponding lubricantconcentration at which two phases are observed. This temperature maximumis typically observed in the range between 5 and 25% lubricant by weightin the refrigerant and lubricant mixture.

For screening purposes, one or two lubricant concentrations wereselected, such as 50% lubricant to represent in some circumstances theanticipated most miscible mixture and 10% to represent in somecircumstances the least miscible mixture. Relative to the examplerefrigerant blend, the four POEs (i.e. POE #1 to POE#4) evaluated allmaintained a single phase at 50% by weight lubricant, but their CSTvaried at the 10% by weight concentration.

Last Miscible Last Miscible Temperature Temperature (50% Lubricant) (10%Lubricant) Lubricant ° C. ° F. ° C. ° F. POE #1 <−20 <−4 <−20 <−4 POE #2<−20 <−4 6 43 POE #3 <−20 <−4 <−20 <−4 POE #4 <−20 <−4 −20 −4

The CST for POE #2 was too high at the 10% lubricant concentration anddid not meet the miscibility requirements. The low CSTs observed for POE#1 and POE #3 indicated that these two lubricants had excellentmiscibility, but suggested that they may exhibit relatively highsolubility, since miscibility and solubility generally trend together(e.g. high miscibility (or maintaining a single phase to a very lowtemperature) generally correlates to high refrigerant solubility). POE#4, exhibited lower but still acceptable miscibility relative to POE #1and POE #3, and exhibited acceptable solubility when used as componentin a lubricant blend (e.g. Oil #9).

FIG. 7 is another chart showing refrigerant solubility of the examplerefrigerant blend with a lubricant blend herein in comparison to theexample refrigerant blend with the POE #1 and relative to R123/mineraloil. In FIG. 7, a known percentage of refrigerant is mixed with the oil,and the solubility is indicated by the vapor pressure above therefrigerant/oil mixture. Assuming the refrigerants have similarpressures, which is the case here since ER-10 is a slightly lowerpressure than R-123), the higher the vapor pressure, the lessrefrigerant that is dissolved in the oil (and thus lower solubility).The lower the vapor pressure, the more refrigerant that is dissolved inthe oil and the less it is able to contribute to the vapor pressure. Ingeneral, for ER-10/POE 1, the vapor pressure is lower at the sameconditions when compared to ER-10/Oil #9 and R-123/baseline MO.

FIG. 8 shows side sectional view of an embodiment of a bearing 800,which may be employed in a compressor, for example in the system shownin FIG. 1. The bearing 800 may be used in a motor of a compressor, suchas for example in a centrifugal compressor. The bearing 800 has an outerrace 802 and an inner race 804. In an embodiment, the inner race 804and/or the outer race 802 may be made of steel, such as may be employedin standard bearing steels in such compressors. The bearing alsoincludes a cage 806 which surrounds the rolling element 808. In anembodiment, the cage 806 may be made of composite material or polymermaterial. In an embodiment, the cage 806 may be made of polyether etherketone (PEEK). In embodiment, the cage 806 may be made of brass. In anembodiment, the cage 806 may be made of riveted steel. In an embodiment,the rolling element 808 may be made of a silicon nitride ceramicmaterial. The bearing 800 in an embodiment can be a heavy duty bearingmade of such materials above and are suitable for use with the lubricantblends and refrigerant blends herein. The lubricant blends herein withthe refrigerant blends herein have been observed to show excellentsolubility and miscibility properties described herein which may bedesired in such equipment using bearing 800, including for example in anHVAC and/or refrigeration unit implemented with a centrifugalcompressor.

With regard to the foregoing description, it is to be understood thatchanges may be made in detail, without departing from the scope of thepresent invention. It is intended that the specification and depictedembodiments are to be considered exemplary only, with a true scope andspirit of the invention being indicated by the broad meaning of theaspects and claims.

Aspects

Any one or more of aspects 1 to 8 may be combined with any one or moreof aspects 9 to 22, and any one or more of aspects 9 to 17 may becombined with any one or more of aspects 18 to 22, and any one or moreof aspects 18 to 20 may be combined with any one or more of aspects 21to 22, and aspect 21 may be combined with aspect 22.

-   Aspect 1. A lubricant blend composition, comprising:

two or more lubricants, the two or more lubricants including

a first lubricant; and

a second lubricant,

the first lubricant is present at a higher volume percentage than thesecond lubricant, the first lubricant includes a higher viscosity thanthe second lubricant, such that when blended with the second lubricant,the lubricant blend has a resulting viscosity when mixed with arefrigerant, and that exhibits a suitable miscibility and solubilitywithin a desired operating range of a vapor compression system.

-   Aspect 2. The lubricant blend composition of Aspect 1, wherein the    first lubricant includes one or more of POE, PVE, and PAG, and the    second lubricant includes one or more of alkylbenzene (AB),    polyalphaolefin (PAO), mineral oil, and estolide.-   Aspect 3. The lubricant blend composition of Aspect 1 or 2, wherein    the first lubricant is present at or about 60 to at or about 90    percent by volume of the lubricant blend, and the second lubricant    is present at or about 10 to at or about 40 percent by volume of the    lubricant blend.-   Aspect 4. The lubricant blend composition of any of Aspects 1 to 3,    wherein the first lubricant is present at or about 80 to at or about    90 percent by volume of the lubricant blend, and the second    lubricant is present at or about 10 to at or about 20 percent by    volume of the lubricant blend.-   Aspect 5. The lubricant blend composition of any of Aspects 1 to 4,    wherein the first lubricant is present at or about 80 to at or about    85 percent by volume of the lubricant blend, and the second    lubricant is present at or about 15 to at or about 20 percent by    volume of the lubricant blend.-   Aspect 6. The lubricant blend composition of any of Aspects 1 to 5,    wherein the first lubricant is present at or about 85 to at or about    90 percent by volume of the lubricant blend, and the second    lubricant is present at or about 10 to at or about 15 percent by    volume of the lubricant blend.-   Aspect 7. The lubricant blend composition of any of Aspects 1 to 6,    wherein the first lubricant is POE or PVE and the second lubricant    is AB or mineral oil.-   Aspect 8. The lubricant blend composition of any of Aspects 1 to 7,    wherein the first lubricant is POE and the second lubricant is AB.-   Aspect 9. A fluid for a vapor compression system, comprising

the lubricant blend of Aspect 1; and

a refrigerant.

-   Aspect 10. The fluid of Aspect 9, wherein the vapor compression    system is a fluid chiller for an HVACR application.-   Aspect 11. The fluid of Aspect 9 or 10, wherein the fluid chiller    includes a centrifugal compressor.-   Aspect 12. The fluid of any of Aspects 9 to 11, wherein the    refrigerant is a refrigerant blend including two refrigerants.-   Aspect 13. The fluid of any of Aspect 12, wherein the refrigerant    blend includes a first refrigerant at or about 60 to at or about 90    percent by weight and a second refrigerant at or about 10 to at or    about 40 percent by weight.-   Aspect 14. The fluid of any of Aspects 12 or 13, wherein the    refrigerant blend includes a first refrigerant at or about 70 to at    or about 90 percent by weight and a second refrigerant at or about    10 to at or about 30 percent by weight.-   Aspect 15. The fluid of any of Aspects 12 to 14, wherein the    refrigerant blend includes a first refrigerant at or about 80 to at    or about 90 percent by weight and a second refrigerant at or about    10 to at or about 20 percent by weight.

Aspect 16. The fluid of any of Aspects 12 to 15, wherein the refrigerantblend includes a first refrigerant at or about 75 to at or about 80percent by weight and a second refrigerant at or about 20 to at or about25 percent by weight.

-   Aspect 17. The fluid of any of Aspects 12 to 16, wherein the    refrigerant blend includes a blend of R1336mzz(Z) as the first    refrigerant and R1130(E) as the second refrigerant.-   Aspect 18. A vapor compression system including

a compressor;

a condenser;

an evaporator;

an expansion device;

a refrigerant; and

the lubricant blend of Aspect 1 blended with the refrigerant.

-   Aspect 19. The vapor compression system of Aspect 18, wherein the    vapor compression system is implemented as a fluid chiller for an    HVACR application.-   Aspect 20. The vapor compression system of Aspect 19, wherein the    fluid chiller includes a centrifugal compressor.-   Aspect 21. A method of retrofitting a vapor compression system,    comprising:

removing an existing fluid in the vapor compression system, the existingfluid includes a refrigerant and lubricant mixture;

replacing the existing fluid in the vapor compression system with areplacement fluid, the replacement fluid includes a replacementrefrigerant and the lubricant blend of Aspect 1; and

confirming an operating range of the vapor compression system with thereplacement fluid.

-   Aspect 22. A method of reducing the solubility of a refrigerant in a    lubricant blend, comprising:

selecting a refrigerant for application in a vapor compression system;

selecting the lubricant blend of Aspect 1 to be included as a mixturewith the selected refrigerant;

confirming a miscibility of the lubricant blend and refrigerant whenmixed together over a desired operating range of the vapor compressionsystem;

confirming a viscosity of the lubricant blend and refrigerant when mixedtogether over the desired operating range of the vapor compressionsystem.

1. A lubricant blend composition, comprising: two or more lubricants,the two or more lubricants including a first lubricant; and a secondlubricant, the first lubricant is present at a higher volume percentagethan the second lubricant, the first lubricant includes a higherviscosity than the second lubricant, such that when blended with thesecond lubricant, the lubricant blend has a resulting viscosity whenmixed with a refrigerant, and that exhibits a suitable miscibility andsolubility within a desired operating range of a vapor compressionsystem.
 2. The lubricant blend composition of claim 1, wherein the firstlubricant includes one or more of POE, PVE, and PAG, and the secondlubricant includes one or more of alkylbenzene (AB), polyalphaolefin(PAO), mineral oil, and estolide.
 3. The lubricant blend composition ofclaim 1, wherein the first lubricant is present at or about 60 to at orabout 90 percent by volume of the lubricant blend, and the secondlubricant is present at or about 10 to at or about 40 percent by volumeof the lubricant blend.
 4. The lubricant blend composition of claim 1,wherein the first lubricant is present at or about 80 to at or about 90percent by volume of the lubricant blend, and the second lubricant ispresent at or about 10 to at or about 20 percent by volume of thelubricant blend.
 5. The lubricant blend composition of claim 1, whereinthe first lubricant is present at or about 80 to at or about 85 percentby volume of the lubricant blend, and the second lubricant is present ator about 15 to at or about 20 percent by volume of the lubricant blend.6. The lubricant blend composition of claim 1, wherein the firstlubricant is present at or about 85 to at or about 90 percent by volumeof the lubricant blend, and the second lubricant is present at or about10 to at or about 15 percent by volume of the lubricant blend.
 7. Thelubricant blend composition of claim 1, wherein the first lubricant isPOE or PVE and the second lubricant is AB or mineral oil.
 8. Thelubricant blend composition of claim 1, wherein the first lubricant isPOE and the second lubricant is AB.
 9. A fluid for a vapor compressionsystem, comprising the lubricant blend of claim 1; and a refrigerant.10. The fluid of claim 9, wherein the vapor compression system is afluid chiller for an HVACR application, and the fluid chiller includes acentrifugal compressor.
 11. The fluid of claim 9, wherein therefrigerant is a refrigerant blend including, by weight of therefrigerant blend, a first refrigerant at or about 60 to at or about 90percent by weight and a second refrigerant at or about 10 to at or about40 percent by weight.
 12. The fluid of claim 9, wherein the refrigerantis a refrigerant blend including, by weight of the refrigerant blend, afirst refrigerant at or about 70 to at or about 90 percent by weight anda second refrigerant at or about 10 to at or about 30 percent by weight.13. The fluid of claim 9, wherein the refrigerant is a refrigerant blendincluding, by weight of the refrigerant blend, a first refrigerant at orabout 80 to at or about 90 percent by weight and a second refrigerant ator about 10 to at or about 20 percent by weight.
 14. The fluid of claim9, wherein the refrigerant is a refrigerant blend including, by weightof the refrigerant blend, a first refrigerant at or about 75 to at orabout 80 percent by weight and a second refrigerant at or about 20 to ator about 25 percent by weight.
 15. The fluid of any of claim 9, whereinthe refrigerant is a refrigerant blend including R1336mzz(Z) as thefirst refrigerant and R1130(E) as the second refrigerant.
 16. A vaporcompression system including a compressor; a condenser; an evaporator;an expansion device; a refrigerant; and the lubricant blend of claim 1blended with the refrigerant.
 17. The vapor compression system of claim16, wherein the vapor compression system is implemented as a fluidchiller for an HVACR application.
 18. The vapor compression system ofclaim 17, wherein the fluid chiller includes a centrifugal compressor.19. A method of retrofitting a vapor compression system, comprising:removing an existing fluid in the vapor compression system, the existingfluid includes a refrigerant and lubricant mixture; replacing theexisting fluid in the vapor compression system with a replacement fluid,the replacement fluid includes a replacement refrigerant and thelubricant blend of claim 1; and confirming an operating range of thevapor compression system with the replacement fluid.
 20. A method ofreducing the solubility of a refrigerant in a lubricant blend,comprising: selecting a refrigerant for application in a vaporcompression system; selecting the lubricant blend of claim 1 to beincluded as a mixture with the selected refrigerant; confirming amiscibility of the lubricant blend and refrigerant when mixed togetherover a desired operating range of the vapor compression system;confirming a viscosity of the lubricant blend and refrigerant when mixedtogether over the desired operating range of the vapor compressionsystem.